I mean, I feel like there should be something about either acting or theatre or even musicals. They have plays in anime but is there any that revolve around theatre? If there are, what are the titles and story lines?

Well seeing as you have listed acting, I would suggest Skip Beat!
It revolves around a young girl named Kyoko who aims to get revenge on Fuwa Sho by getting into show business and acting. During the series she gets several acting roles and the whole series can be found right here on Crunchyroll
I hope you'll consider it, I found it really good!

AMAZING series, likable characters - and the main girl is REALLY likable-. The manga is far better, and thought it was started in the 70's, it continues on today. Art is old school, but the story is SUPER EPIC.

Aaaand it is the second best selling Shoujo manga of all time.

Skip Beat is like a modern version of it. But it is so similar, it almost feels like a rip off.